This invention is generally directed to photoconductive imaging members with charge transport compound components. More specifically, the present invention is directed to layered imaging members with charge transport compounds selected in some instances, for example, diaryl biarylylamine derivatives. The aforementioned charge transport compounds, or components possess a number of advantages including excellent charge transporting characteristics; they are environmentally safe and nonhazardous; and these compounds, which possess structral simplicities which simplify their synthesis by known economic processes including the well known Ullman condensation, can be obtained in excellent yields. Also, the charge transport compounds of the present invention exhibit excellent compatibility with known resinous binders, such as polycarbonates, polyesters, and the like, thereby inhibiting or substantially eleiminating the undesirable crystallization thereof in the transport matrices. Additionally, the charge transport compounds illustrated herein enable photoconductive imaging members can be selected for electrophotographic imaging and printing processes for an extended number of imaging cycles exceeding, for example, at least 50,000 cycles. Furthermore, the charge transport molecules or compounds of the present invention possess acceptable solubility in common organic solvents such as halogenated, especially chlorinated hydrocarbons, tetrahydrofuran, toluene, xylene, and the like, thus enabling improved coatability thereof by various processes such as spray, dip and drawdown coating techniques. In one embodiment of the present invention, the imaging member is comprised of a supporting substrate, a photogenerating layer, and in contact therewith a charge transport layer comprised of the diaryl biarylylamines of the formulas illustrated herein. The charge transport layer can be located as the top layer of the imaging member, or alternatively it may be situated between the supporting substrate and the photogenerating layer.
The formation and developement of electrostatic latent images on the imaging surfaces of photoconductive materials by electrostatic means is well known. Numerous different photoconductive members for use in xerography are known such as selenium, alloys of selenium, layered imaging members comprised of aryl amine charge transport layers, reference U.S. Pat. No. 4,265,990, and imaging members with charge transport layers comprised of polysilylenes, reference U.S. Pat. No. 4,618,551. The disclosures of the aforementioned patents are totally incorporated herein by reference. However, the layered imaging members incorporating the diaryl biarylylamine layer of the present invention are, for example, economically more attractive than, for example, the members of the '790 and '551 patent in respect of material and fabrication costs, and possess the other advantages illustrated herein. More specifically, the diaryl biarylylamine derivatives charge transport compounds of the present invention can be synthesized from readily available inexpensive starting materials by cost effective synthetic processes.
There are also known photoreceptor materials comprised of other inorganic or organic materials wherein the charge generation and charge carrier transport functions are accomplished by discrete contiguous layers. Additionally, photoreceptor materials are disclosed in the prior art which include an overcoating layer of an electrically insulating polymeric material, and in conjunction with this overcoated type photoreceptor there have been proposed a number of imaging methods.
Specifically, layered photoresponsive device including those comprised of photogenerating layers and transport layers are disclosed in U.S. Pat. No. 4,265,990, and overcoated photoresponsive materials containing a hole injecting layer overcoated with a transport layer followed by an overcoating of a photogenerating layer and a top coating of an insulating organic resin, reference U.S. Pat. No. 4,251,612. Examples of generating layers disclosed in these patents include trigonal selenium and vanadyl phthalocyanine, while examples of the charge transport layer that may be employed are comprised of the aryl diamines as mentioned therein. The '990 patent is of particular interest in that it discloses layered photoresponsive imaging members similar to those illustrated in the present application with the exception that the charge transporting component of the members of the present invention are comprised of diaryl biarylylamine derivatives of the formulas illustrated herein. These members can be utilized in electrophotographic methods by, for example, initially charging the member with an electrostatic charge and imagewise exposing to form an electrostatic latent image which can be subsequently developed to form a visible image. Other representative patents disclosing layered photoresponsive devices include U.S. Pat. Nos. 4,115,116; 4,047,949 and 4,081,274.
As a result of a patentability search there were located U.S. Pat. Nos. 4,725,518; 4,664,995; 3,265,496; 3,180,730; 4,471,039 and as background interest 4,585,772 and 4,769,302. Disclosed in the '518 patent is an electrophotographic imaging member containing a charge transport layer by forming a mixture comprising a charge transporting aromatic amine compound of one or more compounds having the general formula illustrated in the Abstract, a polymeric film forming resin in which the aromatic amine is soluble, and from about 1 part per million to about 10,000 parts per million of a protonic acid or a lewis acid having a boiling point greater than 40.degree. C., reference the Abstract of the Disclosure, and column 12, beginning at line 17. In the U.S. Pat. No. 3,265,496 , there is mentioned as photoactive compounds a tertiary amine that could be biphenyl diphenyl amine, see column 2, beginning at line 19, and particularly line 27, and column 2, beginning at line 50. In U.S. Pat. No. 3,180,730, there are disclosed triphenyl amines as photoactive compounds, see columns 1 and 2, for example; while U.S. Pat. No. 4,471,039 suggests at column 5 that triphenyl amines can be selected as hole transport compounds for photoconductive materials.
As a result of a patentability search in related U.S. Pat. No. 4,869,988 with the listed inventors Beng Ong and Giuseppa Baranyi, entitled Photoconductive Imaging Members With N,N-bis(biarylyl)aniline, or tris(biarylyl)amine Charge Transporting Components, the disclosure of which is totally incorporated herein by reference, there were located Japanese Koni abstract J5 8002-849, which discloses photoconductors comprising a laminate of a carrier generation layer A and a charge transport layer B, which layer contains an amine derivative of Formula I, which amine is similar to the charge transport compounds of the present invention, a carbazole derivative of Formula II, and a polymeric organic semiconductor having a condensed aromatic ring or hetero ring in the side chain; Ricoh Japanese abstract 61-132953, which discloses an electrophotographic sensitive body with a trisazo pigment of Formula I and a charge transfer layer of Formula V, which transfer layer is similar to the charge transport compounds of the present invention; and as background or collateral interest U.S. Pat. Nos. 4,233,384; 4,273,846; 4,450,218; 4,637,971 and 4,719,963. In the aforementioned copending application, there is disclosed an improved layered photoconductive imaging member comprised of a supporting substrate, a photogenerating layer optionally dispersed in an inactive resinous binder, and in contact therewith a charge transport layer comprised of bis(biarylyl)aniline derivatives (I), tris(biarylyl)amine derivatives (II), or mixtures thereof dispersed in resinous binders.
Examples of specific charge transporting components disclosed in the aforementioned copending application include, N,N-bis(4-biphenylyl)-3,5-dimethoxyaniline (Ia); N,N-bis(4-biphenylyl)-3,5-dimethylaniline (Ib); N,N-bis(4-methyl-4'-biphenylyl)-3-methoxyaniline (Ic); N,N-bis(4-methyl-4'-biphenylyl)-3-chloroaniline (Id); N,N-bis(4-methyl-4'-biphenylyl)-4-ethylaniline (Ie; N,N-bis(4-chloro-4'-biphenylyl)-3-methylaniline (If); N,N-bis(4-bromo-4'-biphenylyl)-3,5-dimethoxyaniline (Ig); 4-biphenylyl bis(4-ethoxycarbonyl-4'-biphenylyl)amine (IIa); 4-biphenylyl bis(4-acetoxymethyl-4'-biphenylyl)amine (IIb), 3-biphenylyl bis(4-methyl-4'-biphenylyl)amine (IIc), 4-ethoxycarbonyl-4'-biphenyl bis(4-methyl-4'-biphenylyl)amine (IId), and the like.
There is also disclosed in Belgium Patent 763,540 an electrophotographic member having at least two electrically operative layers, the first layer comprising a photoconductive layer which is capable of photogenerating charge carriers, and injecting the photogenerated holes into an active layer containing a transport organic material which is substantially nonabsorbing in the spectral region of intended use, but which is active and that allows injection of photogenerating holes from the photoconductive layer and allows these holes to be transported through the active layer. The active polymers may be mixed with inactive polymers or nonpolymeric materials. Also, there is disclosed in U.S. Pat. Nos. 4,232,102 and 4,233,383, the disclosures of which are totally incorporated herein by reference, the selection of sodium carbonate doped and barium carbonate doped photoresponsive imaging members containing trigonal selenium.
While imaging members with various charge transporting substances, including aryl amines, are suitable for their intended purposes, there continues to be a need for improved members, particular layered members, which are comprised of new economical charge transporting substances. Further, there continues to be a need for layered imaging members wherein layers are sufficiently adhered to one another to allow the continuous use of such members in repetitive imaging systems. Also, there continues to be a need for charge transporting substances which are compatible with various common resinous binders, such as polycarbonates or polyesters, thereby ensuring the long-term stability of the members. Also, there continues to be a need for charge transporting substances that are also useful as protective overcoating layers, and as interface materials for various imaging members. Furthermore, there is a need for charge transport compounds that are nontoxic, and wherein such members are inert to the users thereof. A further need resides in the provision of novel efficient charge transport compounds which are readily accessible synthetically from inexpensive commercial starting materials.